In recent years bicycling has become a very popular recreational and physical-conditioning activity. For one form of recreational bicycling, bicycle touring, it is desirable to equip the bicycle with a rear carrier rack or front carrier rack or both and to attach panniers to the racks to carry clothing, food, camping equipment and the like. Along with the increasing popularity of bicycle touring has come the development of a variety of rack and pannier systems.
It has long been recognized that an important objective in designing a bicycle bag is to enable the rider to carry equipment in such a way as to minimize movement of the equipment relative to the bicycle, inasmuch as shifting of loads carried on the bicycle relative to the bicycle produces undesirable swaying motions that significantly increase the effort of a rider required to control the bicycle, mainly in the form of considerable attention to steering to maintain balance and tracking. In the case of rear panniers, for example, swaying of the panniers relative to the rearward portion of the bicycle creates an effect known as tail wagging, which the rider has to compensate for by a combination of steering and body movements to maintain balance.
An important development in panniers was made by the assignee of the present invention and is the subject matter of U.S. Pat. No. 4,271,996. According to that development, a pannier frame system is provided in which a bag of flexible, durable material is given shape and load-carrying capability by a three-dimensional internal frame comprising a back member and a top member, the top member being joined to the back member in such a way as to provide load-carrying support for the fabric bag from the top member. As part of the pannier system of the aforementioned patent, an attachment system is included which comprises a pair of hooks fastened to the upper portion of the pannier frame and adapted to be hooked over the top of the longitudinal top bars along each side of a rear carrier rack. One end of a tension spring is connected to the back part of the internal frame of the pannier at a point well up the back of the bag, and the other end of the spring is connected to a J-hook or the like fastened to a lug on the rear dropout of the bicycle frame. The lower portion of the spring is held against the back of the pannier frame by an external strap. When the pannier is mounted on the rear rack, the spring force holds the pannier down on the rack to prevent the hooks from releasing from the top bar. The engagement of the lower portion of the spring by the strap restrains the lower portion of the bag from swaying out laterally. The pannier system of U.S. Pat. No. 4,271,966 has been very successful in the marketplace and under most circumstances provides excellent restraint against the swaying of the panniers. Moreover, it is very convenient to use, in that to detach the pannier from the rack the user need only lift up on the pannier with sufficient force to overcome the force of the tension spring, thereby dislodging the upper hooks from the top bar of the rack. The user then lowers the pannier to relax the spring and allow the spring to release from the inverted J-hook at the bottom.
There are, nonetheless, shortcomings in the attachment system described above. For one thing it is desirable to provide a fairly substantial spring force to hold the bag down on the rack. This means that it is sometimes necessary for the user to hold the rear part of the bicycle down with one hand and lift the pannier with the other to place the hooks over the rack. Moreover, the user has to apply a fairly large force to detach the pannier and, for that matter, to attach it to the rack. Another problem is that because the spring force is, of course, limited and can be overcome, it is possible for the pannier to be detached from the rack by an abrupt upward force, such as can result from going over a sharp bump in the road.
Hine-Snowbridge, Inc. of Boulder, Colo., which markets several lines of bicycle products under the name Kirkland, has recently introduced commercially a pannier suspension system under the designation "Leverlock". The Leverlock system comprises a pair of spaced-apart inverted J-hooks mounted adjacent the top of a pannier, a pair of lower hooks tensioned by elastic cord for attachment to the lower portions of the struts of the rear carrier rack, and a large plastic lever pivotably connected at approximately its mid-point to a pivot axis on the pannier back frame. A triangular lock plate is also attached to the pivot axis and is arranged to be adjusted to a desired position rotationally with respect to the pivot axis through an angle defined by an arcuate slot that receives a lock screw associated with the pannier frame. The lock plate has a projecting lug that captures one end of the lever in a locked position in which a locking surface at the other end is engaged under the underside of the side rail of the carrier rack platform. The adjustable locking plate allows the user to change the angle of attack between the lever and the top bar, thereby effectively changing the distance between the pivot axis of the lever and the bar of the rack. Releasing and engaging the lever requires the user to push laterally inward on the lever toward the wheel to clear the locking lug on the lock plate. While the Leverlock system is reasonably effective in retaining the pannier on the rear rack against dislodgement caused by abrupt upward forces, the components are of very large size, which makes them somewhat of a nuisance when the panniers are handled off the rack. When in position on the rack, the user has to fish down in a tight area between the wheel and the pannier well below the top of the rack to manipulate the lever to lock or unlock it.